Fuel injection system for internalcombustion engines



E. DODSON MaLrch 4, 1947.

FUEL INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINES 3 Sheets-Shet 1Filed Aug. 25, 1944 T0 ENGINE "FUEL March 4, 1947.

E. DODSON 2,416,797 FUELK INJECTION SYSTEM FOR.INTERNAL coususnon mamasI Filed Aug. 23, 1944 3 Sheets-Sheet 2 W \o o o o v 7 53 z 54 z E.DODSON March 4, 1-947.

FUEL INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed Au' 25.,1944 Sheets-Sheet a I w a M w uu m o w a m o v 1 A 5. I 6 v 3 i qu O O Ow z .1 1 0 oo M l l l l m 3 o o J J a w n w. w a w Patented Mar. 4, 1941UNITED STATE s PATENT OFFICE INJI' JCTION SYSTEM FOR INTERNAL-COMBUSTION ENGINES Edward Dodson, Oaks, Puriton, near Bridgwater,England Application August 23, 1944, Serial No. 550,830 I In GreatBritain September 23, 1943 11' Claims. (c1. 123-119) liquid andcommunicating'through a restricted 1o orifice with aspace filled withliquid, two of the walls of said chamber being constituted by movablepistons, diaphragms or, the like, one of which is linked to thenormally-closed valve and the other of which is linked to a lever or thelike 15 for actuating the throttle valve, and is arranged to be movedoutwardly when the throttle valve is opened. When the throttle valve isopened suddenly to accelerate the engine, the partial vacuum in thechamber is relieved by inward move- 2o ment of the other piston ordiaphragm against a controlling spring, which movement opensthe valve toenrich the mixture, by the extra fuel supplied through the supplementaryconduit,

the second piston or diaphragm closing the valve again when sufficientliquid to fill the chamber. has 'leaked into it through the orifice.Systems of,this character, however, are subject to deleterious eifectsas the result of sticking or leakvalve. By the expression fuel injectionsystem is to be understood a system in which the fuel is injected intothe induction system at a pressure higher than that prevailing'in thesystem at the point of injection. The expression thus excludes 40systems involving the use of a suction carburetter.

The invention also provides 'a fuel injection system for an internalcombustion engine comprising mixture control means for varying thefuel/air ratio of the mixture supplied to the '45 engine, a servomechanism responsive to induction pipe pressure for adjusting saidmixture control means to vary the fuel/air ratio as a desired functionof induction pipe pressure. and an accelerof the throttle valve. toeffect an overriding adiustment of the mixture control means to providea temporary enrichment of the mixture. In the preferred arrangementaccording to the invention, the 'fuelinjection system comprises a 68 2fuel pump for delivering fuel to the engine, means for controlling thedelivery of said fuel pump, and an accelerator pump comprising a cyhndercontaining a pair of pistons or the like, one .of

which is linked to the throttle lever or equivalent throttle actuatingdevice, and the other of which is normally biassed by a spring or theequivalent to a datum position and coupled to said delivery controllingmeans and effective to enrich the mixture when moved against its spring.the space between the pistons being filled with liquid and communicatingby way of a restricted orifice with a supply of said liquid, thearrangement being such that displacement of the first piston consequentupon sudden accelerating movement of the throttle lever causes, byvirtue of the restricted flow of liquid through said orifice, asympathetic movement of the second piston against its spring to effecttemporary enrichon sudden opening movement of the throttle 35 ,ator pumpwhich is effective, on sudden opening ment of the mixture. v

Thus the first piston may, during periods of acceleration, execute asuctionistroke, and cause the second piston to be sucked into thecylinder against its spring, and remain there until sufficient liquidhas leaked into the space between the pistons.

The second piston may be arranged to enrichthe mixture, when displacedagainst its spring,

by varying the eifective stroke of the injectionpump. Alternatively itmay be arranged to control a metering orifice through which the fuel isfed by said pump.

Forms of fuelinjection system according to the invention as applied toan aircraft engine will now be described in detail, by way of example,with reference to the accompanying drawings in which:

Fig. 1 is a diagrammatic showing of the complete installation,

Fig. 2 is an enlarged view showing, also diagrammatically but; ingreater detail, the accelerator pump and associated mechanism forvarying the fuel flow, of the arrangement of Fig. 1,

Fig. 3 is a diagram, similar to Fig. 2, showing a second embodiment.

Fig. 4 is a diagrammatic view of part or an installation, similar toFig. 1, but in which the rate of flow of fuel to the ne is varied bycontrolling the delivery stroke of a fuel pump.

Like reference characters indicate like parts throughout the figures.

Referring first of all to Fig. 1, air is fed to the engine along theinduction pipe ill by an engine-driven supercharger II, the flow of airbeing controlled by a throttle valve l2.

' 33 (see Fig. 2).

' 33 in the piston 3|.

in the induction pipe |6 (see Fig. 1).

3- 'To the pilots throttle armed lever |4 rotatable about a pivot IS;The

arm |6 of the lever I4 is connected, by alink lever I3 is fixed a three-7 connected, by a link 22 to a cam 23, which pivots about the centre 24.This cam forms the subject of my copending application Serial'No.556,831

and its function is described below. The third arm 25 of the lever I4 isconnected to the upper pump 21 and cam 23. The position of the meteriing valve 36 is also subjectto changes in boost exhaust pressure,induction temperature and 'back pressure, as later described.

The lower piston 3| of the accelerator pump is normally maintained by aspring 32 at the bottom of the pump'cylinder and in contact with stop|3|, and is formed with a restricted orifice A by-pass conduit 34connects the upper and lower ends of the pump cylinder,

7 l4 moves to the chain-dotted position, and the upper'piston 26 of theaccelerator pump is lifted. The partial vacuum in the space between thetwo pistons causes ,the lower piston 3| to rise against its spring 32,the lower piston remaining in the raised position until the partialvacuum is relieved by leakageof fluid through the Orifi e A non-returnvalve 36 is provided in the upper piston 26 to allow escape of fluidfrom between the two pistons during movement of the pilots lever todecelerate.

The piston rod ofthe lower piston 3| is connected to the right-handendof a lever 31, the other end of which is. connected to a device forimposing a correction on thefuel supply for changes in induction temprature. This is constituted by a Bourdon tube 36 connected bya capillarytube 39 with a thermometer bulb 46 46 and tubes 38, 39 are filled with aliquid having a high coefiicientbf expansion.

, The lever 31 is connected intermediate its ends, by a link 4|, withthe left-hand end of a'lever 42. The other end of lever 42 is connectedto the piston rod of a servo piston 43, and via av ilink GI and an arm6| to a cam Which is rotatable about the centre 45. Intermediate theends of the lever 42 is pivoted a rod 46 connected 7 exhaust backpressure through a conduit communicating with the exhaust pipe 52 (seeFig. 1)-.

The bulb,

The lower end of the double capsule stack 41,. 56 is connected to arelay piston valve 53 of the doubleJand type, controlling communicationbetween the cylinder for the servo piston 43 and a pressure inlet 54 andexhaust outlets 55. As will readily be seen downward movement of thevalve 7 53 results ,in upward movement of the servo piston 43 and upwardmovement of the valve 53 causes the piston 43 to move ,down, the lever42 acting as a follow-up lever to restore the valve 53 to the neutralposition. The position of the piston 43 in its cylinder, and thereforethe setting of the cam 44 are thus determined by the boost pressure, theinduction temperature and the *exhaust'back pressure. Downward movemehtof 'the piston 43 causes the cam 44 to rotate anti-clockwise to enrichthe mixture as described below.

A sudden movement of the pilots throttle lever to open the throttlewill, by raising the lower piston 3| of the accelerator pump, cause atemporary upward movement'of the relay valve 53. and therefore 1-,temporary downward movement of theservopiston 43. The accelerator pumpthus overrides the capsule stack and .provides a temporary enrichment ofthe mixture.

Against the cam 44 bears a roller 56 on one end of a floating lever 51connected at the other end to a follower 58 which bears against the cam23. Spring I59 (Fig. 1) maintains the roller 56 and follower 58 incontact with cams 44 and 23 respectively. The lever 51 is centrallyconnected to the metering valve 36 (Fig. 1) by a link 59. Th cam 44 isso shaped that, as the servo piston 43 descends in its cylinder, thelink 51 will be rocked clockwise about its right-hand end, so liftingthe valve 36 to increase the flow offuel to the engine.

The cam 44 is designed to give an economical mixture over the range ofcruising boost, but a richer mixture at the higher boosts, theenrichment amounting to sayh35% at take-off boost. The cam 43 has aconcentric portion A which gives a weak mixture at cruising boosts, butwhen the pilots throttle lever is moved to a position calling for power,the raised portion B of this cam comes beneath the lower endof thefollower 58,

thus rocking the floating link 51 anti-clockwise about its left-hand endto enrich the mixture, the enrichment amounting to say 15% when thepilots lever is in the full throttle position.

While, in the embodiments illustrated, in Figs. 1 and 2, the link 59 iscaused to vary the fuel/air ratio'by adjusting thearea of the fuelmetering orifice defined by the valve 36, it may as an alternativeachieve this result by varying the effective stroke of the fuel pump.Such an arrangement is shown in Fig. 4. Here the area of meteringorifice I36 remains fixed and link 59 operates arm 259 to vary, in knownand convenv tional fashion, the effective stroke of a variable directlyto the servo valve 53, is applied between the servo piston 43 and thecam 44, the lower piston 3| of the accelerator pump acting on theleft-hand end of a floating link 66, connected at its right-hand endto-the'link 6| operating .the cam 44 and connected intermediate itsends, via a link 62, to the piston rod of the servo piston 43. In thiscase the lever 31 and link 4| of Fig. 2

are dispensed with, and the Bourdon tube 33 acts directly on thelcft-hand end of the follow,- 1 up lever 42. a

what I claim as my invention secur by Letters Patent is:

1. A fuel injection system for an internal combustion engine havinga'throttle valve,.comprising means for supplying fuel and air to theengine, mixture control means forvarying the fuel/air ratio of themixture supplied to the en gine, a servo mechanism responsive toinduction pipe-pressure for adjusting said mixture control and desire tomeans to vary the fuel/air ratio as a desired function ,of inductionpipe pressure, and an accelerator pump which is efi'ective, on suddenopening .-bers, abiassing device for biassing the otherpressure-responsive member to a datum position and a connection betweensaid other pressure-responsive member and the delivery controlling meansarranged to enrich the mixture, by delivfuel pump for delivering fuel tosaid injection nozzle, means for controlling the delivery of said fuelpump, an accelerator pump comprising a cylinder and a pair of pistons insaid cylinder/a throttle actuating member linked to one of the pistonsand arranged to give it a suction stroke during periods of acceleration,a spring for biassing the other piston towards the associated end of thecylinder, a restricted outlet from the space between said pistonscommunicating with a supply of liquid which normally fills said space,

and a connection between said other piston and the delivery controllingmeans arranged to enrich the mixture, by delivery of additional fuel tosaid, nozzle on movement of said other piston against its biassingspring.

4. A fuel injection system for aircraft engines as claimed in claim 1,comprising capsules responsive to boost-pressure and to exhaust backpressure for controlling the servo mechanism, a device responsive toinduction temperature for further controlling the servo mechanism and acam for transmitting movement from the servo mechanism to the mixturecontrolmeans, said .cam determining 'the relationship between fuel/airratio and boost pressure. I

' 5. A fuel injection system for aircraft ,engines as. claimed in claim1, comprising capsules responsive to boost pressure and to exhaust backpressure for controlling the servo mechanism, by operation of a controlvalve associated therewith, a device responsive to induction temperaturefor further controlling the servo mechanism 5 erator pump serving toeffect bodily displacement "81A fuel injection system for an internalcom-y and a cam for transmitting movement from the servo mechanism tothe mixture control means,

said cam .;detc'rmining the relationship between fuel/air ratioand'boost pressure and said accelof said capsules and control valve.

6.v A fuel injection system'as. claimed in claim 1," in which theaccelerator pump is linked to'a-control valve associated with the servomechanism.

f I 7. A fuel injection system as claimed in claim 1, comprising alinkage connecting the servo mechanism and the mixture control means,and'an operative connection between said linkage and the acceleratorpump.

"fuel/air ratio of the mixture supplied to the engine, a variable datumboost control device for positioning the throttle valveto maintain theboostnpressurecata valueselected by said pilots lever, mechanismoperated by said control device for adjusting said mixture controlmeansto vary the fuel/air ratio as a desired function of selected boostpressure, and means operated by saidv pilots lever for effecting, onsudden movement of said lever to select a higher boost, a temporaryoverriding adjustment of said mixture control cry of additional fuel tosaid nozzle, on movement r means to enrich the mixture.

9. A fuel injection system for an internal combustion engine, having athrottle valve and a pilot's lever for adjusting said valve, comprisingan injection nozzle, a fuel pump for delivering 40 induction pipepressure for operating said fuel of said lever, a temporary movement ofsaid fuel control valve to vary the rate of flow of fuel to said nozzleas a desired function of induction pipe pressure, and means operated bysaid pilots lever for eifecting on sudden accelerating movement controlvalve to increase the rate of flow of fuel to said nozzle.

10. A fuel injection system for an internal combustion engine, having athrottle valve and a pilots lever for adjusting said valve, comprising55 said metering orifice, a variable datum boost control'device forpositioning the throttle valve to of said fuel control valve to increasethe rate oiv an" injection nozzle, a fuel pump for delivering fuel tosaid nozzle, a. metering orifice for controlling the rate of supply offuel to said nozzle, a fuel control valve for controlling the effectivearea of maintain the boost pressure at a, value selectedby said pilotslever, mechanism operated by said boost control device for adjustingsaidfuel control .00 valve to vary the rate of supply of fuel to saidnozzle as a desired function of boost pressure, and

- means operated by said pilots lever for effecting,

on sudden movement of said lever to select a higher boost, a temporaryover-riding adjustment flow of fuel to said nozzle.

11. A fuel injection system for an internal combustion engine, having athrottle valve and a pilots lever for adjusting said valve, comprisingan injection nozzle, a fuel pump for delivering fuel to said nozzle,means for controlling the delivery of said fuel pump to vary the rate of7 I fuel as ,a desired function of induction ptessurre, UNITED STATESPATENTS and means operated by said pilot's lever or Num I e effecting,on sudden movement of said lever to E2 ga": y: 1935 select a higherboost, a temporary overriding ad- 2:092 685 V1 e1 1 Sept 1937 justmentof said delivery controlling means to 5 2141*594 Cole 1938 increase therate of flow of fuel to said nozzle. 46 M 1940 EDWARD DODSON 1,995,800Dodson M 2 1935 REFERENCES CITED FOREIGN PATENTS The followingreferences are of record in the Number Country D t file of this patent:523,895 England July 25, 194,0

